An electromagnetic fuel injector normally comprises a cylindrical tubular body having a central through hole, which acts as a fuel conduit and terminates with an injection nozzle regulated by an injection valve controlled by an electromagnetic actuator. More specifically, the injection valve has a pin connected rigidly to a movable armature of the electromagnetic actuator, and which is moved by the electromagnetic actuator between a closed position, and an open position opening the injection nozzle in opposition to a spring which keeps the pin in the closed position.
An electromagnetic fuel injector of the type described above is illustrated, for example, in U.S. Pat. No. 6,027,050A1, which relates to a fuel injector having a movable assembly defined by a pin which, at one end, cooperates with a valve seat, and, at the opposite end, is integral with a movable armature of an electromagnetic actuator. The movable assembly is guided at the top by a guide cooperating with the armature, and is guided at the bottom by the end portion of the pin sliding inside a guide portion of the valve seat.
A drawback of known injectors of the type described above lies in rebound of the pin on impact with the valve seat of the injection valve, and which is not fully damped by the spring connected to the movable armature. On the contrary, it may even produce oscillation of the movable armature, thus resulting in successive, undesired opening/closing of the injection nozzle and, hence, undesired fuel injection into the combustion chamber, so that the amount of fuel actually injected into the combustion chamber involves a certain random element.
In an attempt to eliminate rebound of the pin against the valve seat of the injection valve, fuel injectors have been proposed with hydraulic and mechanical antirebound devices. Known antirebound devices, however, are complex and therefore expensive to produce, and normally fail to effectively eliminate rebound of the pin against the valve seat of the injection valve.